“…should still strive to reduce intake of red and processed meat, which tend to contain high amounts of saturated fat and sodium.”

And so on.

By now, we see these lines, roll our eyes, and keep on moving down the path that seems to be helping us. But that’s us, people who pay attention to nutrition news and stay abreast of the literature. We may be able to write off these breathless articles without thinking we’re going to die because we ate that bunless burger the other day, but our parents, our friends, our colleagues may not be so well-equipped. They’re worried about our health, and who can blame them? If you take mainstream health articles at face value, articles which confirm what your doctor is probably telling you, you would do the same.

Hi Mark,

Have you heard about the latest study saying that we’re all killing ourselves? I’m personally not that worried, but I’ve been getting a ton of frantic and/or smug emails from concerned and/or smug friends and loved ones. I’d love to be able to point them toward something to explain the results. Think you could tackle it?

Thanks,

Matt

This is another in a long line of observational studies that find associations between processed meat intake and early death so that journalists can feel superior about something while writing easy articles (with lots of copy and pasting from the last one). I mean, aren’t they all the same? “Regardless, [name of expert] is quick to urge consumers to cut back on [delicious, Primal food that has supposedly been killing us humans, bite by bite, for tens of thousands of years] and reduce the overall percentage of [saturated fat[8] or cholesterol[9] or sodium[10]] in their diets.” If you’ve read one, you’ve read ’em all.

I feel like I’ve done all this before. I’m experiencing the distinct sensation of deja vu, kinda like when you have a dream and it feels like you’ve had it before, but when you wake up and try to piece it all together with a clearer mind, you realize that it was a totally unique vision and just an artifact of the nature of dreamscape. This may not involve showing up late to the big exam in the nude or falling from a cliff and waking up right before you hit ground, but it’s strangely familiar, isn’t it?

Being hit with one of these studies every couple months like clockwork wears down a man. It boggles me how people can grapple with the same questions (oftentimes using the same datasets), never coming to a conclusion, never even getting any closer to the truth, always dancing around on the edges. I get that this is how science works – you can’t leap to conclusions that aren’t actually there – but why not ask some different questions? It’s the same thing over and over again.

And yet it will be thrown in your face, so let’s go over it.

The study used data from the European Prospective Investigation into Cancer and Nutrition[11] (EPIC) study, which collected complete information on diet, smoking status, physical activity, and BMI from almost a half million men and women without stroke, cancer, or heart disease. They grabbed a decade’s worth of data along with “clinical endpoints” (death from various causes), and have since been running the numbers to see the effect of various factors – usually a particular category of food or nutrient – on mortality. Today’s study was about the effect of red meat and processed meat on all-cause mortality.

What did they find?

The highest intake of processed meat[12] was associated with a 44% increase in all-cause mortality. That could be death from bladder cancer, myocardial infarction, or car accident. Anything goes. This association was reduced to 24% after adjusting for smoking, but it wasn’t eliminated. Adjusting for other confounders, like energy intake, alcohol intake, body weight, activity levels, and produce intake, was also unable to totally make up the difference. Doing all the right things and avoiding all the wrong things still didn’t remove the association. Interestingly, the lowest intake of processed meat (none) was associated with more mortality than low or moderate consumption of it. Perhaps some meat-based nutrients[13] are so vital that getting them via Lunchables is better than nothing?

Intake of unprocessed red meat was barely associated with increased all-cause mortality until adjusting for other confounding factors, after which point the association vanished completely. These confounding factors included overall energy intake, alcohol intake, smoking, body weight, activity levels, and produce intake.

There’s a definite healthy user bias[14] when it comes to processed meat. People who ate the most processed meat also ate the least amount of fruits and vegetables[15]. They also smoked and (the men, at least) drank a lot and tended to avoid the gym. Red meat eaters, too. As I said, they tried to account for these confounding variables, but I’m skeptical they can do so completely.

I’m just happy they’ve actually started differentiating between red and processed meat. It used to be that “red meat” was cautioned against on the strength of studies which lumped fresh rare rib-eyes and braised short ribs with Oscar Meyer hotdogs, bologna, and ham Lunchables, but some of the latest ones have realized there’s a difference between the two. Next, it’d be nice to see what happens if they start accounting for what people eat alongside processed meat; I’m pretty sure white bread buns, strange goopy seed oil sauces, and french fries all play their role, too.

Another pleasant thing about this study is that the articles it’s spawned have generally been high quality. Confounding variables, the difference between causation and correlation, and the fact that fresh red meat had no significant associations with mortality were all mentioned and addressed in most of the articles[16] I came across.

So, to sum up: This was an observational study that only showed correlations. It did not establish causation.

Assuming the correlations indicated causation (which, you know, we have no way of knowing), fresh red meat[17] has no effect on mortality. Processed meat does, but this effect is lessened when you account for the fact that processed meat eaters also lead generally unhealthy lifestyles bereft of exercise and produce and replete with smoking, overeating, and, for men, drinking[18]. Even so, those adjustments were purely mathematical. Even the authors of the study “could not exclude residual confounding,” the general unhealthy lifestyle effect. You can’t quantify general unhealthiness, recklessness, psychological stress, and all the other factors that affect our health and mortality. They didn’t track things like checkups at the doctor, either.

All that said, this research isn’t saying anything we’re not already aware of.

Don’t make processed meat your major source of animal products. Eat steak, not those weird processed meat sticks they sell at gas stations. I’ve said this before[19].

And yes, bacon[20] is delicious, but it shouldn’t replace real, actual meat in your diet. A pound of bacon for breakfast is a fun thing to have when your vegetarian[21] friends stay over, though – I’ll admit that.

Eat your produce, folks. It’s good for you, and it may even reduce the formation of carcinogenic compounds when co-ingested with meat (steak and salad, anyone?). That could explain the relative reduction in mortality among people who ate lots of fruits and vegetables with their processed meat.

Don’t overcook your meat. The authors speculate that high-heat processing and the subsequent formation of heterocyclic amines (HCA) could explain the association between processed meat and mortality. Other studies[22] have certainly found a connection between high-heat cooking, HCA, and prostate cancer, so I wouldn’t be surprised if there was a mechanism there.